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SubjectRe: [PATCH] filp->f_pos not correctly updated in proc_task_readdir
On Mon, Mar 16, 2009 at 08:34:57AM +0000, Al Viro wrote:
> On Mon, Mar 16, 2009 at 02:44:31PM +0800, Zhang Le wrote:
> > filp->f_pos only get updated at the end of the function. Thus d_off of those
> > dirents who are in the middle will be 0, and this will cause a problem in
> > glibc's readdir implementation, specifically endless loop. Because when overflow
> > occurs, f_pos will be set to next dirent to read, however it will be 0, unless
> > the next one is the last one. So it will start over again and again.
>
> Eh... Here's what's really going on:
>
> proc_..._fill_cache() API is rather kludgy and far too convoluted. In
> particular, it calls filldir() and passes file->f_pos to it, expecting
> the caller to update file->f_pos between the calls. proc_task_readdir()
> uses that sucker, but doesn't update ->f_pos until the very end. As
> the result, d_off of direntries produced by it gets screwed.
> Broken-by: commit 61a28784028e6d55755e4d0f39bee8d9bf2ee8d9
> Author: Eric W. Biederman <ebiederm@xmission.com>
> Date: Mon Oct 2 02:18:49 2006 -0700
>
> [PATCH] proc: Remove the hard coded inode numbers
>
> Patch is fine, but I'd rather rip the layers of ..._fill_cache() abstractions
> out and see what falls out. Anyway, for -rc your variant is definitely the
> way to go.

Except this bit:

fs/built-in.o: In function `proc_task_readdir':
compr_zlib.c:(.text+0x434b8): undefined reference to `__cmpdi2'
compr_zlib.c:(.text+0x434d4): undefined reference to `__cmpdi2'


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